Reflex integraph



Feb. 6, 1951 I Filed Aug. 4, 1947 R. E. GLOVER 2,540,111

REFLEX INTEGRAPH 6 Sheets-Sheet 1 Fig.1 44

INVENTOR.

Robe/"7 E. Glover R. E. GLOVER REFLEX INTEGRAPH Feb. 6, 1951 6 Sheets-Sheet 2 Filed Aug. 4, 1947 INI ENTOR. Roberf E. Glover Feb. 6, 1951 R. E. GLOVER 2,540,111

REFLEX INTEGRAPH Filed Aug. 4, 1947 6 Sheets-Sheet 5 :82 INVENTOR.

R. E. GLOVER REFLEX INTEGRAPH Feb. 6, 1951 6 Sheets-Sheet 4 Filed Aug. 4, 1947 Fig.5

INVENTOR.

Roberf E. Glover R. E. GLOVER REFLEX INTEGRAPH Feb. 6, 1951 6 Sheets-Sheet 5 Filed Aug. 4, 1947 Fig. 6

SPILLWAY OUTFLOW-THOUSANDS OF CUBIC FEET PER SECOND kw NI 1 22:; M: m

A R EA ACR ES 200 250 VOLUM E THOUSL .N D S OF ACRE F EET JNVENTQR.

Feb. 6, 1951 R. E. GLOVER 2,540,111

REFLEX INTEGRAPH Filed Aug. 4, 1947 6 SheetsSheet 6 Fig. 7

ELEVATIONS O O O O Tl ME- DAYS Q) m ,4 (i) m K) w@' g F| g I q 1 2ST:-:

O O O O O 0 0o :2 2 3 2 2 m FLOOD lNFLOW-THOUSANDS 0F CUBIC FEET PER SECOND INVEN TOR.

Roberf 56/01/01" M ff;

Patented Feb. 6, 1951 UNITED STATES PATENT OFFICE REFLEX INTEGRAPH Robert E. Glover, Denver, Colo. Application August 4, 1947, Serial No. 766,120

21 Claims. (01235-61 (Granted under the act of March 3, 18 83, as

The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to me of any royalty thereon in accordance with the provisions of the act of April 30, 1928 (ch. 460, 45 Stat. L. 467).

This invention relates to a reflex integraph, a device for solving differential equations.

A large number of differential equations exist for which there are no solutions in terms of known functions. Solutions of such equations have been sought by mechanical means but the machines used have been large, complicated, expensive, difficult to adapt to a new solution and requiring particular skill on the part of the operating personnel.

It is an object of this invention to provide a mechanical device for solving differential equations, said device being relatively compact, simple of construction, and inexpensive to manufacture.

It is a further object of this invention to provide a mechanical integrating device which may be quickly and easily adapted to solve various types of mathematical problems.

It is also an object to provide a mechanical integrating device which may be operated and adapted to new problems by moderately skilled personnel.

It is also an object to provide a mechanical integrating device which will be free from errors due to lost motion. I 7

Other objects will be apparent from the following description taken in. connection with the accompanying drawing in which:

Fig. 1 is a schematic view of an adaptation of the Abakanowicz motion as used in this invention) Fig. 2 is an elevational view of the follower motio'ri'used in this invention.

Fig. 3 is a schematic View of a device embodying' the principle of this invention.

Fig. 4 is a schematic view of the multiplier device used with this invention.

Fig; 5 is a schematic view of an alternate system which may be used with this invention.

The integrating device used in this invention is the Abakanowicz motion designated generally at}! in Fig. 1 where it is shown with positioning and following means. In that figure tracks and H run transversely of the machine and are fixed thereto. A carriage [2, arranged to run along track I I, is provided with a pointer and has pivoted thereto a bar 15. Bar' I5 is arranged to be;-'slidable at all times axially through a fixed .piyot; Ia;- Pivot. isifixed with respect to. the

amended April 30, 1928; 3'70 0. G. 757) frame of the machine by means not shown. A carriage I8 is arranged to be slidable at all times axially along bar 15. Fixed to carriage l8 perpendicular to bar 15 is crossbar l9. f :i

' Carriage 2| is constructed to run transversely along track Ill and has pivoted thereto a crossbar 22. Crossbar 22 has fixed at right angles thereto a sharpaedged disc 24 pivoted for rotation about its axiswhichis' parallel to the crossbar 22. Carriage 2i carries pointer 25. Links 21 and 28 are pivotally connected at the ends thereof to the ends of crossbars I9 and 22. Links 21 and 28 are of equallength as are crossbar's l9 and 22. Table 30 moves longitudinally and preferably is covered by a sheet of paper.

The parallelogram formed by crossbars l9 and 22 and links 2! and 28 causes disc 24 to always remain parallel to bar 15. Sharp-edged disc 24 will not slide along its axis ofrotation but must always move along a path the tangent to which at every point is the trace of the plane of the disc. If pointer I3 is caused to trace curve 32 on table 30 as table 30 moves longitudinally, pointer 25 will trace curve 33 on table 30,curve 33 being the integral of curve 32. If pointer" 25 carries a pencil, curve 33 will be generated on the tracing of curve 32. If it represents a distance measured along the axis in a direction counter to the table motion and 111 and 1/2 represent the ordinates of the curves 33 and 32, re-

spectively.

where K is some constant which depends upon the distance of the fixed pivot from track 'll. Then by integration- Associated with the integratlng motion is a positiom'ng device comprising a cable 36 running over wheels 38 and 4|, one of said wheels being on each side of table 3 Wheels 38 and M are provided withknobs 4a and 45 respectively to allow manual rotation of the wheels and thus manual po'sitioning'of the carriage 12. Cable 38 is arranged to pull carriage l2 in either direction transversely of table 30, and is here shown attached to pointer I3 to avoid confusion in the drawingbetween cable 36 and track H.

J In Fig. 2 is shown an elevational view of the positioning means. Cable 36passes around 270 of wheels 38 and 4! and around'450 of wheels- 3,3,.andgd0. Wheels '38 and 41 have respectively; "fixedt ereto knobs 44 and 15. .Preferably' knobs supply 1|. veter 66' are three resistors-12, 13 and 14.

3 such as 44 and 45 are afiixed on both sides of wheels 38 and 4|. These knobs allow convenient positioning of carriage |2 from either side of table 36. In this invention table 30 is preferably transparent and has a translucent paper strip 3| fixed thereto for movement therewith. Pointer l3 carries a pencil 43 to record its trace on paper 3|. due to lost motion.

Associated with wheel 40 is a potentiometer 45- comprising resistor 4! and sliding contact 4 8'.

Contact 48 is fixed to wheel 4!! so that rotation' The cable 36 is kept taut to eliminate errors :light spot 93 thereon.

along track 35 and is positioned therealong by. I

cable 35' which runs over wheels 38' and 4! to which are fixed knobs 44 and 45' respectively. Wheels 38' and 4| correspond to wheels 38 and 4| of Fig. 2 and the general construction of the follower is similar to that shown in Fig. 2. It

will be seen that if the follower pointer 42 is caused by manipulation of knobs 44' or 45' to .stay in alignment with output pointer 25 of the integrator motion, the follower potentiometer 46 of Fig. 2 will produce a voltage corresponding to .the position of pointer 25.

To insure greater accuracy, in place of the con- ;struction shown in Fig. 1 in which cable 35 is .-;fixed to carriage l2 or pointer I3, a follower mo- 151011, 811011 as indicated at 34, may be used to In this alternative con- 4 position carriage |2. struction a transverse follower track corresponding to track 35 is fixed to the machine frame ad- "jacent the pointer.

;- Referring now more particularly to Fig. 3 for ,a description of a system embodying-this invention, two integrators and 52 are provided, each f which ,is an Abakanowicz motion as shown in .Fig. 1 at [4. Follower motions 53. 54, 55,. and

-56, substantially as shown in Fig. 2 are also pro- 'vided, Input follower 56 is provided with a pointer 98 corresponding to pointer |3 of Fig. 2. Transparent table 30 is shown passing under in- ,tegrators 5| and 52 and follower motions 53-56. Translucent paper strip 3| is fixed to table 30 and is cut away to show galvanometer 65 under table 30. Means, such as the rack 5| and screw 62, are provided to move table 3|] in a longitudinal direction.

The pointer I3 of integrator 52, corresponding to pointer l3 of-Fig. l, is positioned transversely of table 30 by follower motion 55. Pointer of integrator 52 corresponds to pointer 25 of Fig. 1. j Follower54, pointer l3, integrator 5| and pointer 25" is constructed in the same manner as the corresponding'parts '55, ;|3', 52, and 25' respectively. 1 Follower 53 is similar in construction to the ,follower shown in Fig. 2. Follower 53 operates a potentiometer 56 which corresponds to poten- -;-tiometer 46 in Fig. 2 and includes resistor 57 and contactor 68. Potentiometer 66 receives current through potentiometer Hi from power Connected in shunt with potentiom- Resistor I3 is connected between resistors 12 and 14, the latter two being ballast resistors and resistor 13 having an adjustable tap 15. It is thus Seen that adjustment of potentiometer l5 varies theiangecf voltage coveredby potentiometer :;66..-.---.The voltage appearing across taps stand- 15 diminishes toward zero as tap 68 approaches its mid-position and changes polarity as tap 68 goes through its electrical mid-position. Adjustment of the tap 75 on resistor 13 varies this electrical mid-position.

Taps 68 and T5 are connected through reversing switch 18 and connecting double-throw double-pole switch 19, collecting bus 82 to balanced direct current amplifier 83.

Balanced direct current amplifier 33 is connected to wire coil 85 of galvanometer 6B. Coil 85 is suspended for rotation in a spring suspension and is mounted between magnet poles 135 and 81. Coil 85 carries a mirror 89 fixed for rotation therewith. Light source 93 produces light which is reflected from mirror 89 and focused by optical system 9| upon paper strip 3| to form The above mentioned spring suspension, not shown, tends to keep mirror,,89 in a neutral position but current flowing from amplifier 83 through coil 85 causes the coil and mirror to rotate in a direction and magnittude depending on the direction and magnitude of the current flow. Rotation of mirror 39 causes spot 93 to move transversely of paper strip 3| under the path of travel of pointer l3. Follower motions 5s, 55 and 56 are constructed in a manner similar to the device shown in Fig. 2. Followers 55 and 55 include potentiometers corresponding to potentiometer 55 of follower 53. These potentiometers are included in networks 35 and which also include power supplies, and resistors corresponding to elements 70-75 of the network associated with follower 53.. Follower 55 differs from followers 53, 54 and 5B in that it has no potentiometer or associated electrical network.

It will be seen that in operation of the device shown in Fig. 3, pointer 25 traces a curve which is the integralof the curve traced by pointer l3". If pointer i3" is maintained in alignment with pointer 25', then the curve traced by pointer 43 is the second derivative. of the curvetraced by pointer 25". As pointer 55 is made tofollow pointer 25", network 94 produces a voltage which is indicative of the position of pointer 55. The center position being represented by zero voltage and either side of the center position being. rep? resented by voltage of opposite polarities. The scale, or range, of this voltage is regulated by potentiometer 10 while the center position is reg; .ulated by tap E5. The sense in which this voltage'is applied to collector bus 82 is determined by reversing switch 78. The voltage may be eliminated entirely from bus 82 by switch .19. The doublepole double-throwswitchqlfi is ar ranged to connect the bus on through if unit 34 is disconnected therefrom- Unitsfi l, 35,- and 95 may be connected simultaneously to the bus so that their voltages may be added or subtracted before being fed to the balanced direct current amplifier. 1

The pointer of input follower 55 may be caused by manual control to follow-a curve, perhaps empirical, plotted on strip 3|. The voltages indic'ae tive of the positions of pointer i3"? and the pointer of input follower 55 are produced'by net? works 95 and 96, respectivelsnand mayibejadded to bus 82 in the sense desired.

The sum of the voltages collected by bus 82. is applied to amplifier 83 and controls the position of light spot 93.

Fig. 4 shows an alternative means for inter-,- connecting some of the elements of the electrical hireuit associated with afollower'and' also shows an additional network to allow the multiplying of two quantities before feeding them to the bus.

In Fig. 4, follower I has a construction similar to that shown in Fig. 2. Follower I00 is associated with a potentiometer IOI. Potentiometer IOI includes a resistor I02 and a sliding contactor I03 which are connected to a three element jack I05. Potentiometer IOI may be connected to network I04 through jack I05, plug I08, cord I0I, plug I08 and jack I09 so that resistor I02 is connected across resistors III, H2, and H3 which are connected in series, with resistor H2 in the middle. Contactor I03 of potentiometer IOI may be connected through plug jack and cord elements I 05--I09 and through reversing switch I I4 to jack II5. Jack II5 may be connected through plug H6, cord H7 and plug H8 to jack I20 of balanced direct current amplifier I25. In network I04 direct current power supply I23, potentiometer IIO, resistors III--II3, and reversing switch II4 correspond to elements II, I0, 'I2-I4, I8. respectively, of Fig. 3.

Follower motion I00 also controls potentiomet er I30 which comprises resistor I3l and contactor I32, adapted to be associated withnetwork I39. Potentiometer I30 may be connected through jack I34, plug I35, cord I36, plug I31 and jack I38 so that resistor I3I is connected across resistors I40, I42 and I43 connected in series, :resistor I42 being between resistors I40 and I43. Cord and plug set I35I3I may also operate to connect contactor I32 through reversing switch I45 to jack I4'I. Contactor I44 adjustable along resistor I42 is also connected through reversing switch I45 to jack I41. The output of balanced direct current amplifier I25 is connected across potentiometer I48. Resistors I40I43 are connected across one end of potentiometer I48 and its adjustable contactor. ""Jack I4I may be connected through plug I50, cord I5I and plug I52 to jack I53 of bus 82. Bus 82 is the same as shown in Fig. 3, jack I53 taking the place of switch I9.

The extra potentiometer shown in'Fig. 4 may be mounted in the follower wheel corresponding to wheel 39 in Fig. 2. Alternatively the follower motion could be arranged so that any small number of potentiometer units each containing a connecting jack may be slipped on a follower shaft.

The jack and plug arrangement shown in Fig. 4 may be used with all of the potentiometers, such as potentiometer 65, in Fig. 3 and also to connect the electrical network associated with each follower to the bus 82. This arrangement permits of a maximum of flexibility with a minimum of elements, allowing a network such as I39 to be inserted between the usual network I04 and the bus 82 to form a multiplier unit for any follower.

The multiplier unit shown in Fig. 4 is essentially two units such as 95 in Fig. 3 connected in series. The voltage appearing at jack M1 is therefore proportional to the product of the positions' of the two potentiometers included in the multiplier circuit. Scale setting is accomplished by adjustment of potentiometer I48.

It is to be understood-that while a manually operated type of this device has been described for purposes of simplicity it is contemplated that automatic followin could be arranged through the use of well known devices. if it were desirable to do so. 1 As an example of the use of reflex inte- 6 graph described above, the steps will be outlined? in the solution of the differential equation which is to be solved subject to the conditions? y=1 when 2::0

The second derivative is assigned to follower 55 (in Fig. 3). Since each of the integrator motions 52 and 5| makes an integration, the middle follower 54 will trace out is da: 7

and the left-hand follower will trace out y. The integrator motions 52 and 5I would perform these integrations for any curve traced out by follower 55 and it will be necessary to impose the conditions represented by Equation 3 if the curve traced by pointers 25"-65 is to be a solution of Equation 1. To accomplish this the y follower 53 is connected to the bus through switch I9 while reversing switch I8 is placed in its minus" position. Switches I9 and 19" associated respectively with followers 54 and 56 are placed in their lower or out position so that only the network associated with follower 53 is connected to the bus 82 and to amplifier 83. The light spot will now follow the motion of the y follower and since it appears under the pointer I3 of follower 55, the required relation between 1 and the second derivative can be maintained by keeping the pointer and the spot in coincidence. This is done by manually operating follower 55 in the arrangement shown in Fig. 3 or may be done automatically.

It is now necessary to decide on some scales.

These cannot all be chosen arbitrarily since they are not all independent. One of the scales which are measured normal to the :c axis, may be assigned a trial value as may the a: scale which is measured along the axis. The following trial scale values are now arbitrarily assigned.

y, 1 inch to .25 .r,-l inch to .20

If the distance from the fixed pivot I8 to track II as seen in Fig. 1 is 5 inches, and if the middle follower I3 of Fig. 3 is displaced 1 inch and table 30 is moved 5 inches, the pointer 25 of integrator 5| will travel 1 inch away from the x axis. The scale assigned for must make the area swept out by pointer I3" consistent with the travel along the y axis. The increment on the 1 scale is equal to the travel along the Z/ axis multiplied by the y scale value. The area sweptout by pointer I3 is equal to the product of the scale value, the ire cscalervaluemnd itl'lGiIllIIIlbEMUf square inches swept out.

If the at, y,

scale values are represented by-SK, S0, S1, and S2, respectively, and since similar i'statements apply to both integrators 5i and 52, the following is true:

By algebraic process the'followin values are obtained since So='.25 an'd Sx=f20 mime- Reference to' Equation 3 showsthat'with these forth in Equation '2. Tableao is-moved to its "extrem'e' ri'ght'position. The y pointers 55 v and 2-5 aremovedto scale position LOO-and pointers l3" and' 25' "are moved *toscaiie position 0. The sharp wheel's corresponding to wheel 24'of Fig. 1) of'integrators 5! and 52*arebrou-ght to rest on the paper 3 I,

pointer I 3' of integrator 52 -is registered with spot 93 and the machine is ready to run.

"In a manually operated integraph, such "as is shown in Fig. 3, three operators are required. The first operator keeps rpointer i 3 in coincidence with spot 93'by manipulating the 'knobs of Tollower 55. The second operator keeps poiriter l3 in alignment with pointer 25' by manipulationof the-knobsof follower 5.4. The .third opera- .torQkee'ps pointer 65 :inalignment with pointer 25"'by manipulation .of theknobs ofifollower 53. The ,pencils, attached to the pointers l3'., l3", and 165 of Figure 3, trace out the solution and its first 'two derivatives on the paper attached to the moving table during the run. "Inthis application, the input follower 56 is not used.

To explain the use ofthe integraph in an iteration procedure, an outline will be given of the method cf computing .the maximum Water level in a reservoir when a floo'd comes into it. "The reservoir is usually provided with a spillway whose rate of discharge'depends on the depth of water in the reservoir. The-surface-area'of the reservoir also varies with its water depth :in 2, manner determined by the topography of the site. 1

The .:rate at which the reservoir ri'ses is expressed by the followingequation:

y "Q'q 11F A "(15) "where :yirepresents' the "elevation or the reservoir "waiter surface '(feet), .ltgtim'e KsecondS) :q, {the spillway discharge (ftZ /se'c.), *Afithe area of 1 the reservoir water surface ii-til The data ,for anyac'tual case are usually "pre- .sen'tedlin the form of curves, such asthose shown *on Figures 56 and 7. IA scrutiny of these graphs will show that q is not proportional to 311 an?! that A varies withy. Considered as'adifferential equation, therefore, Equation 5 is non-flineai "in type because the dependent variable appeals insometmanner'other'than to the first'power, Equations of'this'type are very difiicult "to treat by formal methods and the usual procedure :is toobtain an'approximation' by 'ari'thmeticmeans.

In proceeding with the solution by use "of the reflex in'tegraph,a linear approximation is writtenfor'the discharge as follows:

where K1 is some constant.

"The *area A is assumed to be "constant at some average :value -Ao. Then the following equation is :approximately :true:

ll Q- 1y dt A0 .(6)

This :form of discharge curve -q==K 1y gives an approximation 'of the type i shown by the dotted line iniFig. 6 anvzlurnakes it. necessary to measure 1; from the spillway crest level. Equationd -bein'g of the linear type, can be readily set up and solved on the Lintegraph.

The curve solution.

Tz'zbl'e 39 is now m'o'ved'while inputpohiterllS follows curve Q/Ao as plotted on paper '31 and while pointer '13 follows light spot -93. :yis then traced ion paper '3! by the pencil carried by pointer This first approximation of y is shown .as the=dotted curve in .Fig. .7.

This zfirst approximation is used to :obtain :a closer approximation by the procedure of adding theterm 4 to bothsi'des of'Equation 5 to obtain the fol1o wing:

9 If Equation '7 is compared with Equation 6 written in the form it 'will be seen that the right-hand member Q A has been replaced by plus a correction term Eg A0 A curve previously followed by the input follower 55, Equation '7 may be solved in the manner previously described for Equation 6 to obtain a second approximation. In a similar manner the second approximation may be used to obtain a third approximation and the third may be used to obtain a fourth. In this case it will be found that the fourth approximation agrees with the third. This means that the fourth approximation, in fact, satisfies the non-linear Equation since the identical terms which were added to both sides of it; to obtain Equation 7 did not change the equality,- and therefore, the solution for Equation 7 will also satisfy Equation 5. In this -manner a non-linear equation has been solved by the use of a machine arranged for the solution of linear equations.

It may be noted that the .approximations which were introduced as temporary expedients have nowv all been eliminated. The final curve is shown on Figure 7 labelled Reservoir level.

:In the cases where the procedure applies, it may beoutlined as follows:

(cX'Write the nonlinear equation.

(b) Write a linear approximation representing ff. the true conditions s closely as possible, and

" solve it by use of the integraph.

(0) 'Add the linear terms containing the depend- .Y ent variable to both sides of the nonlinear equation and group the terms so as to make it possible to solve the new equation as a linear equation when the nonlinear terms have been computed on the basis of the first .f approximation.

(ZDT'Solve the new equation on the integraph to obtain a second approximation.

(6') Use the second approximation to get a third, and repeat until there is no further change. The stable solution is the desired solution of the non-linear equation.

1A case which will illustrate the use of the multipliercircuit is the following. An important equation in the theory of surge tanks is of the form da 2(a) +114) This equation is nonlinear because the square of the first derivative appears and it is diiiicult to treat by formal methods. The machine is adapted for solving this equation by replacing the idler pulley corresponding to wheel 39 of Fig. 2, on follower 54 with a rheostat pulley, corresponding to wheel 40 of Fig. 2. Follower 54, which traces out in this case, therefore controls two sliders. This makes the output of the multiplier circuit propor- This case is set up on the machine in the manner described for Equation 1 except that the output of the multiplier circuit is fed to the bus in addition to the output from the y follower. This case illustrates the use of the machine to solve a non-linear differential equation directly.

The use of a machine of this type for solving a system of equations directly may be illustrated as follows: Suppose it is desired to solve a system of equations such as:

Subject to the conditions: z=0, y=1, and

when 50 0.

For this purpose three integrators 5|, 52 and 5| and a duplicate bus system 82' are required as shown in Fig. 5. Integrators 5|, 5| and 52 are the same as integrators 5| and 52 in Fig. 3. Followers 53, 54 and 55 are thesame as the followers of the same number in Fig. 3 while followers 53' and 54' are the same as followers 53 and 54, respectively. Networks 94 and 94' are the same as network 94 shown in Fig. 3. Amplifier 83 and galvanometer 60 are the same as the elements of the same number in Fig. 3. Amplifier 83' and galvanometer 60' are the same as amplifier 83 and galvanometer 6|], respectively. Light spots 93 and 93' are identical with light spot 93 in Fig. 3. Buses 82 and 82' are constructed and connected to the other elements as is bus 82 in Fig. 3.

In Fig. 5 the 1/ integration could be performed by integrators 5| and 52 and the 2 integration by integrator 5|. The indicator light spots 93 and 93' would then be arranged to appear at the input sides of integrators 52 and 5|, respectively. A solution of Equation 9 for the highest order derivative in each case gives:

' -If the two buses 82 and 82' are now arranged 11; so that 82! imposes the 2y, magnitude on the, input of integrator 51' and the other imposes the magnitude on the input of integrator 52, the machine will draw outthe curves for dx. dx

followers 53, 54, 55, 53' and. 54', respectively; providing the indices are set to the above-men-. tioned values of a, y, and

aim.

atthe start of the run. This example illustrates, the, use, of a, machine. of this, type for solving. parametric difierential equations directly...

It will be seen that this invention provides a reflex integraph simple; oi manufacture, free of lost motion, convenient touse, highly flexible and adaptable to the solution of, a number of, types of mathematical problems. shown herein are exemplary only and many,mod-,- iiications will occur to those skilled inv the art. without departing from the spirit of. the invention as defined in the appendedclaims.

What is claimed is:

2. an d' 1'. Flexible integrating apparatus comprising a.

ti ansversely of said-table iii-juxtaposition to the input mea-nsoi one of said integrating devices, and means selectively responsive to a function of" the output traverse of atleast one of said:

integrating devices for controlling the movement of said indicator.

I 2.- Flex-ible integrating apparatus according to claim- 1, at least one of-sa-id driven means controlling a variable'impedance in accordance with the position of the input pointer controlled by saidv last mentioned driven means, said indica tor controlling means comprising an electrical circuit selectively connectable to include, said variable impedance and to control the movement-of said indicator in accordance with a function of the position of" saidlastmentionedinput pointer.

36 Flexible integrating apparatus according-to claim 1, at least one of said driven means ismanually adjustable to align its input pointer with the precedin output pointer,- said last mentioned driven means controlling a variable im-- pedance in accordance with-the position of its input pointer, said indicator: controlling means-- comprising an electrical circuit selectively connectable to include said variable impedance and to control the movement of said indicator in accordance with a function of the position of said last mentioned input-pointer.

4. Flexible integrating apparatus according to claim; 1, in which saidtable is, light.,-.pemious The. embodiments.

.independent 12 and in which said, indicator comprises, a; light beam projected through said table,

5. Flexible integrating apparatus comprisinga table, a plurality of seriately related integrating devices each having an input pointer and an output pointer arranged to travel transversely; of said table, each integratin device being arranged so that its output pointer indicates the integral of the indication of its input pointer, driven means controlling the position of the input pointer whereby the input pointer'of'each succeeding integrating device may be caused to follow the output pointer of each preceding integrating device, at least one independent input.

I device having a pointer arranged-to travel transversely of said table, drivenmeans for adjusting the transverse position of, said last mentioned pointer, means for producing relative longitudinal movement, between. said table and: said! devices, an indicator, control means adapted move, said, indicator transversely. of "said. table-.411. juxtaposition tov the input end of one'of saidii' integrating devices, said indicator control -meansa.

being simultaneously responsive: to a function of the traverse of said. independent input device and to the output traverse of at least one of the said output means for controlling the traverse of said indicator.

6. Flexible integrating apparatus; according-"tor claim 5, at least one of said driven means controlling a variable impedance in accordance with the position of the pointer adjusted by said last mentioned driven means said.w indicae-- tor controllin means: comprising an. electrical; circuit selectively connectable, to. include. said;

variable impedance and to control. saidindica-- tor in accordance withfunctions of thetraverses; of said last mentioned drivenmeans andv said; input device.

"7'. In an apparatus, for solving,mathematical? equations, a table, meansafor movingsaid table;- longitudinally, a. plurality, of,integratingndevices; each having an input pointer; and. anoutput; pointen, said pointers being; constrained. to moves in directions. transverse to. the directirm ofv saith table motion, each integratmg devicezcontrolsling its; output pointerv to trace, the;integral; of? a: curve tracedby. itslinputpointer, saidiintegrata'- ing means being arrangedso. that. the; inputs pointer of: a. succeedin integrating means; may

be caused to follow. the output pointer: 02 a. pres ceding .integratingmeans, indicatingimeanspcone trol means causing said. indicating meansgtdi.

move.- transversely to; the motion .of; said; table adjacent the input pointer of. one ofssaidf inz-i tegrating devices, means for causing said. last mentioned input: pointer tofollowthe: move-:

ments of said indicator; a means associated witheach output-pointerfor producing a measure indicative of the position of said pointer,

collectin means for, applying selected, ones of said measures to control the position of saidindicating means.

18.' The combination of. claim 7, including. an input device. having a, pointer, means adapted to cause saidi'last'. mentioned pointerto move transversely ofisaidtablemeans,

adapted to produce ameasure of. the. position of said input device, said. collecting means. being;

.;;adapted to. apply said, last measure. selectively to control the positionioff said. indicating means;

9. The combination of. c1ai m., 7,,in.which each of the means for producing a measure of position of; thezoutput pointersiincludesa carriageameans adapted...to movesaid. carriage transverselyzr-ofi'.

13 said table, said moving means including an imped ance adjusted in accordance with the position or said carriage.

10. The combination of claim '7, in which the table is light pervious and in which the indicator comprises a light beam projected through said table and focused to form a spot substantially in the plane of said table.

11. The combination of claim '7, in which the integrating devices are Abakanowicz motions.

12. The combination of claim '7, in which the means for producing a measure of the position of said output pointers also includes means for adjusting the range of magnitude of said measure, and means for adjusting the center of said range to a predetermined point.

13. The combination of claim '7, in which the measure of the position of at least one of said pointers is a first voltage, means producing a second voltage equal'to said'first voltage multiplied by a factor, said factor being a function of the position of one of said pointers.

14. In an apparatus for solving mathematical equations, a table, means for moving said table longitudinally, a plurality of integrating devices each having an input pointer and an output pointer, said pointers being arranged to move transe versely to the direction of motion of said table, each integrating device controlling its output pointer to trace the integral of a curve traced by its input pointer, said integrating means being arranged so that the input pointer of a succeeding integrating means may be caused to follow the output pointer of a preceding integrating means, indicating means, control means causing said indicating means to move transversely to the direction of motion of said table adjacent the input pointer of one of said indicating devices, means for causing said last mentioned input pointer to follow the movements of said indicator, a means associated with each output pointer for producing a measure indicative of the position of said pointer, collecting means for applying selected ones of said measures to said control means to control the position of said indicating means, each of the means for producing a measure of position of the output pointers including a carriage, means adapted to move said carriage transversely of said table, said moving means arranged to vary an impedance in accordance withv the position of said carriage.

15. The combination of claim 14, including selectively operable means for inverting the measure of the position of said output pointer before application thereof to the collecting means. I

16. In apparatus for solving mathematical equations, a table, at least one integrating device having an input pointer and an output pointer, means for causin relative longitudinal motion between said integrating device and said table, said output pointer being controlled by said integrating device to trace the integral of a curve traced by said input pointer, indicating means adapted to move transversely of the direction of said relative longitudinal motion and table adjacent said input pointer, means for causing said input pointer to follow the movements of said indicator, means manually alignable with said output pointer for causing said indicating device to move transversely in accordance with a function of the position of said output pointer.

17. In a device for solving mathematical equations, a plurality of integrating devices each havin input means and output means arranged to travel in predetermined paths, the output means being controlled to indicate the integral of the indication of the input means,-the path of the output means of at least one of said integrating devices being in juxtaposition to the path of the input means of at least one other integrating device, an indicator, control means to cause said indicator to move in juxtaposition to the path of the input means of one of said integrating devices, an independent input device arranged to travel along a predetermined path, a series electrical circuit for collecting functions of the traverse of said independent input device and at least one of said integral output means in the form of electric potentials, said series electrical circuit being also for totaling said functions each in the proper electrical sense, said series electrical circuit being arranged to control the traverse of said indicator.

18. In an apparatus for solving mathematical equations, a table, means for moving said table longitudinally, a plurality of integrating devices each having an input pointer and an output pointer, means adapted to cause said pointers tomove transversely to the longitudinal motion of said table, each integrating device controlling its output pointer to trace the integral of a curve traced by its input pointer, said integrating means being arranged so that the input pointer of a succeeding integrating means may be caused to follow the output pointer of a preceding integrating means, indicating means, control means for causing said indicating means to move tI'aHSVGI'SQ-1' ly of said table adjacent the input pointer of one of said indicating devices, means for causing said last mentioned input pointer to follow themovements of said indicator, a means associated with each output pointer for producing a measure indicative of the position of said pointer, collecting means for applying selected ones of said measures to control the position of said indicating means, each of the means for producing a measure of position of the output pointers including a carriage alignable with an adjacent integrator output pointer, means adapted to move said carriage transversely to the motion of said table, said moving means controlling means for varying an impedance in accordance with the position of said carriage, said moving means including the use of a taut cable-like means for transmitting the motion of said carriage to said impedance without the introduction of errors due to sensible mechanical play or lost motion.

19. In apparatus for solving equations, a table, a plurality of integrating devices each having an input pointer and an output pointer arranged to travel transversely of said table, each of said devices controlling its output pointer to indicate the integral of the indication of its input pointer, said integrating devices being arranged so that the input pointer of each succeeding integrating device may be caused to follow the output pointer of each preceding integrating device, means for producing relative longitudinal movement between said table and said integrating devices, said longitudinal movement being in a direction substantially at right angles to said transverse direction, a plurality of indicators, means for causing each of said indicators to move transversely of said table in juxtaposition to the input means of one of said integrating devices, a plurality of collecting means each selectively responsive to a function of the output traverse of at least one of said integrating devices for controlling the traverses of said indicators.

20. In an apparatus for solving mathematical gitatingrgmeans. being-arranged so that the input pointer: of: succeeding integratingmeans: may

be caused .tovfoll'ow: the output pointer offa" pre- 2 ceding: integrating means,- indicatingv means; meanssfori-caiusing saidiindicating means to move transversely of; said; table adjacent the input" poi-men of,; one of ;said'findicating devices, means forvcausingzsaidilast mentioned input pointer to followsthee-movements" of said indicator," a means associatedxwith each 'outputpointer for-producin a-measurei.-indicative of: the position of said-pointerzzcollecting means for applying selected ones of said iimeasures to control the position =of-saidfindi'CEl-tifig means; eachcfthem-eans fonproducing acmeasurewfposition of the output pointers including'a-rcarriagey means *adapted to move said' carriage tr'ansversely" of said table; saicl' moving" meansv zincludin animpedance adjustedby the positionmfsaid carriage, said collecting means. being: a -zseries 1 electrical 'circuit for totalingsaid measures;- electricallyin the proper electrical sense:

2'1:The-combination*of'claim 20,. in which the v indicatorimeans is a light spot, in which the controlz'tmeansformoving the light spot .is. a mirror galvanometer swinging a beam of light focused iHnthB- -IJIaHEOf"the-tableto form said light sp ot,.

andtincwh'ich saidfseries electrical circuit controls age-"40am a'id mirror: gafiranometer; said series eie'ctri 'ai circuitbeing pr'ovided w'ith disconnectionswitches each having two positions, each of saidswitches in one" of said' positions including one of said impedanees insaid'seriescircuitand in=the other position: continuing said series circuit while=exeluding said last mentioned impedance from' the series circuit. W v

RROB'ERT EQ GLOVER:

REFERENCES C'I'IED The; following. references, are oTrecor'd in" the file" of this pat'entfi v UN ITED' STATES PATENTS Number Name Date $113,436 Williams A131; 5, 1938 2,212,799 Sperry" Aug. 2'7, 1940' 2,44%770 Flyer July- 6; 1948 OTHER REFERENCES A small scale-- diiferential arialyser its con-" struction'and operation, 'by 'H'. S.- W. Massey; J, Wj lie, R.-A. Buck ingh'amand' R: Sullivan; Pro ceedings of I the- Royal Irish Academy, v01 XIV; sec: A, ,pag.es-':1'-:18 and:plates-I-V; published O'ctL- 4,1938.

An: all electric-integrator forsolving differed? tial equations? by? Robert N.- Varney Review' of sci'entific Instruments}? Jan.- 1942, vol. 13,- No: 1; i pages; 10-46: inclusive;

The Theory" of 15 Mathematicali Machines, by Francis J. Murray; revised edition; Kings Crown Press;- N: Y5, 1948; pages.- IV T tO IV -IOI 

